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RALEIGH, N.C. — About 10 million people a year shop at Crabtree Valley Mall. But on Tuesday, the flow of people was replaced by the flow of Crabtree Creek. The mall and some cars were temporarily underwater as the remnants of Tropical Storm Alberto moved through.

Under the flood regulations mandated after Crabtree's opening in 1972, buildings have to be elevated. Under the new guideline changes mandated this year, only 50 percent of the property can be developed if it's in the flood plain.

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Under the guidelines, the mall would look much different if were constructed today. It would be half its current size and without a first floor.

City officials said safety is one reason for the mandates. Preventing development from impacting surrounding properties is another.

"The more development you have in the flood plain, you put a building in there, it's displacing water that used to go somewhere and its going to push it over on your neighbor," said Mark Senior with Stormwater Management.

The new Costco at the corner of Six Forks and Wake Forest Roads and the Soleil Center across the street from Crabtree have the new regulations built in. The Soleil high-rise will have no parking on the ground level. Raleigh's tallest skyscraper will also be elevated 15 feet. Even the lobbies will be built above flood stage.

"If you go to the beach, the homes are built on stilts," said Soleil Center spokesman Sanjay Mundra. "So yes, water does come and pass through the botttom, but it doesn't damage your home. It's a similar concept on much larger scale."

Soleil Center developers said the flood might actually help them improve plans for the high-rise. The design team will study what happened during this week's flood to see if any modifications to the project need to be made.